Holograms are being used increasingly in all aspects of graphic communications and packaging, from the high security application of currency and passports, to the mass applications of corporate stationery and consumer product packaging. Through their visual activity, holograms provide users the dual advantage of product promotion and product protection.
As the uses of holography grow, and as new players become involved, it is important to establish a basic understanding of the techniques and terminology of the field. Following, I outline the various types of embossed holograms and suggest additional resources for you to learn more.
From a design or “artwork” point of view, six main holograms (plus a seventh fundamental technique) exist:
* Diffraction patterns are visually the simplest holograms. They vary from rainbow gratings to more complex abstract patterns. Diffraction patterns are often used as background material for overprinting or as a visual accent.
* 2D holograms are pictures or graphics, using the bright, changing holographic colors in place of static printed graphics. The 2D images can be line art, flat compositions or even photographs. With 2D holograms, the color shifts as the hologram is moved, but the images themselves do not move. (i.e. there is no parallax).
* 2D/3D Holograms use multiple layers of 2D art separated visually to give depth to the hologram. Typically, these holograms create a foreground/background separation. The hologram has both color shift and parallax from image plane to image plane as it is moved.
* 3D holograms reconstruct three dimensional objects, giving the visual effects of solids. The 3D object can be a simple geometric shape (sphere or cube) or it can be a more complex natural object like an animal or a human face. With 3D holograms it is possible to “look around corners” and see the sides (if not the backs) of the objects in the hologram.
* Multi-channel holograms combine two or more images, each of which is visible in the hologram from a different angle. Often these holograms flash a name or a logo in and out of view, or show the outside or the inside work of an object. The different channels can be made up of any of the hologram types noted above and are often combinations of several. A “MasterCard” with its on and off world map illustrates this effect.
* Holographic stereograms are conversions of movies or other sequential images into holograms. Stereograms can contain several images to create the effect of a movie sequence playing as the hologram is moved around. The images contained in a stereogram can be simple line art or complex three dimensional images. “William Shakespeare” is an example of a stereogram.
* Micro-Text holograms containing information so tiny, that it’s hard to be seen by the naked eye. You need a normal magnifier to read it.
* Nano-Text holograms containing information so tiny, that it’s impossible to be seen by the naked eye. You need a 30 to 50 times magnifier (or even a microscope or a special device) to read it.
* Computer-generated holograms are increasingly being used in place of manual origination. While computer generation is a means for producing hologram, the technique is important enough to highlight specifically. Computers can be used to scan, enhance and create images and patterns for developing stereograms, as well as 2D and 2D/3D holograms. Often these images cannot exist in the real world.
* Hidden Image – these images can only be retrieved by a laser beam.
Once completed, the holographic artwork is transferred through a process of “Laser Lab Photography” to one or more master shims and a set of additional daughter shims are grown electrochemically from this master, the shims are then combined and used to mechanically emboss the hologram onto the material chosen for the project.
The nature of the final product often imposes limitations on the holographic approach selected. For example, it is currently difficult to combine multiple shims in order to form a seamless large 3D image. Therefore, applications like cartons and wrapping paper tend to use abstract patterns and limited text or logo images. Typically, the following different types of holograms will be used in the following applications:
* Labels : 2D, 2D/3D, 3D, Multichannel.
* Hot Stamping Foil : 2D, 2D/3D, 3D, multi-channel, diffraction patterns.
* Laminated : 2D, 2D/3D, diffraction patterns.